This invention is concerned with thermochemical-energy transport processes and, more particularly, with the CO.sub.2 --CH.sub.4 reforming-mathanation chemical cycle of transporting energy, such as solar energy, to a place of use from a place of generation.
Thermochemical energy transport loops can provide an effective means of transportation energy. Such closed cycle loops, using chemical fluids which undergo reversible heat-absorbing and -liberating reactions are key elements in energy transport systems, whether solar, nuclear, or other energy sources are being harnessed. The invention herein disclosed has been developed in conjunction with a complete system of harnessing solar energy gathered from scattered solar collectors and transported to a central energy-storage station from which on-demand power is generated as needed; however, it is emphasized that the process described is amenable for transporting energy from virtually any source to an energy use area, and the scope of the invention should be so understood.
This invention is particularly concerned with modifications and improvements in the CO.sub.2 reforming-methanation chemical cycle, CO.sub.2 +CH.sub.4 .revreaction.2CO+2H.sub.2. Such a reaction cycle I have found to be particularly well-suited to the collection and transport of solar energy, such as exhibited by the teachings of my earier U.S. Pat. No. 3,972,183. The CO.sub.2 reforming-methanation cycle has been studied before, particularly by Wentorf, U.S. Pat. No. 3,958,625, as a possible alternative to the steam reforming-methanation cycle, H.sub.2 O+CH.sub.4 .revreaction.CO+3H.sub.2 in conjunction with a nuclear energy transport loop. However, this process has several serious flaws; for example, the chemical conduits connected to the energy source must be operated at relatively high temperatures to prevent steam condensation in the lines. Such a process also necessitates the use of costly liquid-gas separators, as well as various steam addition and condensation steps. Further, the transport fluid used in Wentorf has a higher carbon removal temperature, necessitating the transport fluid to operate at higher temperatures than would be preferred.